Blends of polyester and cotton fibers are recognized to readily undergo burning and to pose a fire hazard when utilized in fire sensitive environments. The burning propensity of such blends further is recognized to be particularly acute when the polyester component is present in an appreciable proportion of 50 percent or more by weight based upon the total weight of polyester and cotton fibers.
Heretofore, a variety of approaches has been proposed for attempting to deal with the fire hazard posed by a blend of polyester and cotton fibers. Generally these approaches have involved the chemical or physical application of a protective coating (e.g., an organophosphorus flame retardant) upon the surface of the otherwise flammable fibers usually while in fabric form. It commonly has been found essential to apply the protective coating in a major concentration in order to impart the desired self-extinguishing characteristics to the overall polyester and cotton blend particularly when the polyester component comprises an appreciable proportion of the blend. For instance, an organophosphorus flame retardant commonly is applied to such blends in a concentration of about 25 to 40 percent, or more, by weight based upon the total weight of cotton and polyester fibers to pass the Federal flammability standards for children's sleepwear. However, such relatively major concentrations of the flame retardant have a tendency to impair the otherwise desirable textile properties of the blend (e.g., hand and aesthetic appeal). For instance, fabrics formed from a polyester and cotton blend so treated commonly are deficient in comfort and are stiff and harsh. They also commonly exhibit the undesirable quality of poor dyeability (i.e. duller shades), and poor tear strength and abrasion properties. In the prior art fabric constructions and blend levels also have been limited with successful treatments being limited to blends having a high percentage of cotton (e.g., approximately 75 percent by weight) and to medium and heavy weight woven fabric constructions. Shirt weight fabrics of the commonly used 50/50 and 65/35 polyester/cotton blends have not been able to be successfully treated to be self-extinguishing in a vertical test and be durable to 50 home launderings.
Our commonly assigned U.S. Ser. No. 470,420, filed May 16, 1974, entitled "Flame Retardant Fiber Blend Containing Fibers Which If Present Apart From the Admixture Undergo Burning" generically claims a process for rendering normally burning fibers including a blend of polyester and cotton fibers non-burning, as well as the resulting non-burning fiber blend. Included in intimate physical admixture with the fibers which would normally undergo combustion are discrete additive fibers consisting primarily of a chlorinated and/or brominated aromatic polymer having the inherent ability to render the admixture as a whole non-burning when subjected to the flame. Particularly preferred additive fibers are formed primarily of an aromatic polyester formed from the reaction of tetrabromobisphenol A, isophthalic acid, and terephthalic acid or the ester-forming derivatives thereof. Also, in a particularly preferred embodiment a minor concentration of an oxide of antimony (e.g., antimony trioxide or anitmony pentoxide) is intimately dispersed throughout the additive fibers. Flame retardant fiber blends readily may be formed without a diminution of the textile properties thereof, e.g., hand and aesthetic appeal.
It is an object of the present invention to render flame retardant a physical blend of discrete polyester and cotton fibers which contains a substantial portion of polyester fibers.
It is an object of the present invention to provide a flame retardant admixture of discrete polyester and cotton fibers which contains a substantial proportion of polyester fibers having satisfactory textile properties, i.e., hand and aesthetic appeal.
It is an object of the present invention to provide a flame retardant admixture of fibers exhibiting satisfactory textile properties comprising polyester fibers, cotton fibers, and fibers of a synthetic aromatic polymer containing chlorine, bromine, or mixtures thereof chemically bound to an aromatic ring having a chlorine and/or bromine content of about 25 to 60 percent by weight based upon the weight of the aromatic polymer which is substantially free of an oxide of antimony.
It is an object of the present invention to provide a flame retardant admixture of fibers comprising polyester and cotton fibers wherein the polyester fibers are present in a substantial concentration, and an organophosphorus flame retardant is topically applied to the same in a minor concentration thereby retaining the exhibition of desirable textile properties (i.e., hand and aesthetic appeal).
It is another object of the present invention to provide a flame retardant blend of polyester and cotton fibers which exhibits performance characteristics in areas other than burning propensity which are substantially similar to those of an ordinary blend of polyester and cotton fibers.
It is another object of the present invention to render flame retardant to a degree comparable to that achieved in U.S. Ser. No. 470,420, filed May 16, 1974, a polyester and cotton fiber blend which contains polyester fibers in a major proportion without resorting to a relatively high concentration of additive fibers, the presence of an oxide of antimony or otherwise impairing the desirable textile properties of the same.
It is a further object of the present invention to provide a flame retardant fiber admixture which is non-burning (as defined), comprising a substantial proportion of polyester fibers and cotton fibers, when subjected to flame in accordance with the ignition procedure of the Children's Sleepwear Test (i.e., FF 3-71).
It is a further object of the present invention to provide a flame retardant blend of polyester and cotton fibers which yields a garment having improved comfort.
These and other objects, as well as the scope, nature, and utilization of the claimed invention will be apparent from the following description and appended claims.